Passenger counting system, passenger counting method and passenger counting program

ABSTRACT

A passenger counting system that can count correctly the number of persons present in a vehicle, including persons sitting on the back seat, is provided. The passenger counting system includes an image capturing device  11  which is arranged outside the vehicle and which captures an image of the vehicle from the lateral direction of the vehicle, an image acquisition unit  31  that controls the image capturing device  11  and acquires an image in which the inside of the vehicle is captured as an input image, a profile detection unit  32  that detects a profile of a person from a partial image obtained from the input image based on an image feature amount calculated by using the partial image and outputs a detection result, and a passenger number determination unit  33  that determines the number of persons present in the vehicle based on the detection result.

REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 14/435,326 filed on Apr. 13, 2015, which is aNational Stage Entry of international application PCT/JP2013/005368,filed Sep. 11, 2013, which claims the benefit of priority from JapanesePatent Application 2012-231729 filed on Oct. 19, 2012, the disclosuresof all of which are incorporated in their entirety by reference herein.

TECHNICAL FIELD

The present invention relates to a system that counts the number ofpersons present in a vehicle based on an input image obtained bycapturing an image of the vehicle from outside of the vehicle by acamera, in particular to a passenger counting system, a passengercounting method, and a passenger counting program, which count thenumber of persons present in a vehicle by detecting profiles of personsfrom an input image obtained by capturing an image of the vehicle fromoutside of the vehicle from the lateral direction of the vehicle.

BACKGROUND ART

As a technique related to the present invention, a system is proposedwhich counts the number of persons present in a vehicle based on aninput image obtained by capturing an image of the vehicle from outsideof the vehicle by a camera. PLT 1 and PLT 2 describe techniques thatcount the number of persons present in a vehicle by detecting faces andheads of persons based on an input image obtained by capturing an imageof the vehicle by a camera from a position in front of the vehicle.

CITATION LIST Patent Literature

PLT 1: WO 2008/099146

PLT 2: WO 2011/128668

SUMMARY OF INVENTION Technical Problem

The techniques described in PLT 1 and PLT 2 have a problem that thenumber of persons sitting on the back seat of the vehicle may not beable to count correctly because the input image does not have a clearimage of faces and heads of persons sitting on the back seat of thevehicle.

Therefore, an object of the present invention is to provide a passengercounting system, a passenger counting method, and a passenger countingprogram, which can correctly count the number of persons present in avehicle, including persons sitting on the back seat.

Solution to Problem

The passenger counting system according to the present inventionincludes an image capturing device which is arranged outside a vehicleand which captures an image of the vehicle from the lateral direction ofthe vehicle, an image acquisition means that controls the imagecapturing device and acquires an image in which the inside of thevehicle is captured as an input image, a profile detection means thatdetects a profile of a person from a partial image obtained from theinput image based on an image feature amount calculated by using thepartial image and outputs a detection result, and a passenger numberdetermination means that determines the number of persons present in thevehicle based on the detection result.

The passenger counting system according to the present inventionincludes an image capturing device which is arranged outside a vehicleand which captures an image of the vehicle from the lateral directionand the front direction of the vehicle, an image acquisition means thatcontrols the image capturing device, acquires an image in which theinside of the vehicle is captured from the lateral direction as alateral direction input image, and acquires an image in which the insideof the vehicle is captured from the front direction as a front inputimage, a face detection means that detects a profile of a person from apartial image in the lateral direction input image and detects a frontalface of a person from a partial image in the front input image based onimage feature amounts calculated by using the partial images obtainedfrom the lateral direction input image and the front input image andoutputs a detection result, and a passenger number determination meansthat determines the number of persons present in the vehicle based onthe detection result.

The passenger counting method according to the present inventioncaptures an image of a vehicle from the lateral direction of the vehicleby an image capturing device arranged outside the vehicle, control theimage capturing device, acquires an image in which the inside of thevehicle is captured as an input image, detects a profile of a personfrom a partial image obtained from the input image based on an imagefeature amount calculated by using the partial image, outputs adetection result, and determines the number of persons present in thevehicle based on the detection result.

The passenger counting program according to the present invention causesa computer to execute image capturing processing that captures an imageof a vehicle from a lateral direction of the vehicle by an imagecapturing device arranged outside the vehicle, image acquisitionprocessing that controls the image capturing device and acquires animage in which inside of the vehicle is captured as an input image;profile detection processing that detects a profile of a person from apartial image obtained from the input image based on an image featureamount calculated by using the partial image and outputs a detectionresult, and passenger number determination processing that determinesthe number of persons present in the vehicle based on the detectionresult.

Advantageous Effects of Invention

According to the present invention, it is possible to count correctlythe number of persons present in a vehicle, including persons sitting onthe back seat.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] It depicts an explanatory diagram illustrating an overview of afirst exemplary embodiment of a passenger counting system according tothe present invention.

[FIG. 2] It depicts a block diagram illustrating a configuration of thefirst exemplary embodiment of the passenger counting system according tothe present invention.

[FIG. 3] It depicts a flowchart illustrating an operation of the firstexemplary embodiment of the passenger counting system according to thepresent invention.

[FIG. 4] It depicts an explanatory diagram illustrating an overview of asecond exemplary embodiment of the passenger counting system accordingto the present invention.

[FIG. 5] It depicts a block diagram illustrating a configuration of thesecond exemplary embodiment of the passenger counting system accordingto the present invention.

[FIG. 6] It depicts a flowchart illustrating an operation of the secondexemplary embodiment of the passenger counting system according to thepresent invention.

[FIG. 7] It depicts a block diagram illustrating a main part of thepassenger counting system according to the present invention.

DESCRIPTION OF EMBODIMENTS

Next, exemplary embodiments of the passenger counting system accordingto the present invention will be described with reference to thedrawings.

Exemplary Embodiment 1

FIG. 1 is an explanatory diagram illustrating an overview of the firstexemplary embodiment (exemplary embodiment 1) of the passenger countingsystem according to the present invention. FIG. 2 is a block diagramillustrating a configuration of the first exemplary embodiment of thepassenger counting system according to the present invention.

As illustrated in FIG. 1, the passenger counting system of the presentexemplary embodiment includes an image capturing device 1 which isarranged outside a vehicle and which captures an image inside thevehicle from the lateral direction of the vehicle (the left or rightdirection when the traveling direction is defined as the forwarddirection) and a passenger counting device 2 that counts the number ofpersons present in the vehicle based on the image captured by the imagecapturing device 1.

The image capturing device 1 may be, for example, a still camera thatcaptures a still image or a video camera that captures a moving image.

As illustrated in FIG. 2, the passenger counting device 2 includes animage acquisition means 21 that controls the image capturing device 1and acquires an image in which the inside of the vehicle is captured, aprofile detection means 22 that detects a profile of a person based onthe image acquired by the image acquisition means 21, and a passengernumber determination means 23 that determines the number of personspresent in the vehicle based on a result detected by the profiledetection means 22. Each means included in the passenger counting device2 is realized by an information processing device such as, for example,hardware designed to perform specific arithmetic processing or a CPU(Central Processing Unit) that operates according to a program.

The image acquisition means 21 controls the image capturing device 1 andacquires an image in which the inside of the vehicle is captured. Theimage acquisition means 21 may acquire an image in which a vehicle of animage capturing target is captured by controlling the image capturingdevice 1 according to passing timing of the vehicle, which is obtainedfrom a sensor that detects the presence of the vehicle, such as, forexample, a passage sensor and a weight sensor arranged on a course onwhich the vehicle travels. The image acquisition means 21 may controlthe image capturing device 1 to continuously capture a plurality ofimages and to input the images to the image acquisition means 21, andthe image acquisition means 21 may determine whether or not an image ofthe inside of a vehicle is captured by performing image processing suchas detecting a window frame by template matching and acquire an image inwhich the inside of a vehicle, which is an image capturing target, iscaptured. Further, the image acquisition means 21 may acquire aplurality of images in which a vehicle being an image capturing targetis captured.

For example, when the image acquisition means 21 controls the imagecapturing device 1 by using a passage sensor, the image capturing device1 and the passage sensor are installed after the positional relationshipbetween the image capturing device 1 and the passage sensor aredetermined so that the image capturing device 1 can capture a person ona back seat when the passage sensor detects a vehicle. The imageacquisition means 21 can capture the person on the back seat at adesired angle of view by capturing an image of the inside of the vehicleby controlling the image capturing device 1 according to detectiontiming of the passage sensor. Further, the image acquisition means 21may acquire a plurality of images in which a vehicle is captured whichis an image capturing target.

The profile detection means 22 calculates an image feature amount byusing a partial image surrounded by a rectangle with a predeterminedaspect ratio, which is obtained from an image acquired by the imageacquisition means 21 (hereinafter referred to as an input image) anddetermines whether or not the partial image includes a profile of aperson based on the image feature amount, and thereby detects a profileof a person from the input image. The profile detection means 22 mayoutput information indicating whether or not each partial image includesa profile of a person as a detection result or may output a scoreindicating a likeness of a profile of a person in an image included ineach partial image as a detection result.

The profile detection means 22 may determine a range of the partialimage based on, for example, the size of a profile of a person in aninput image, which varies according to the distance between the imagecapturing device 1 and the vehicle. The profile detection means 22 maylimit the range of the partial image to a predetermined range in whichinside of a vehicle may be captured. The profile detection means 22 maylimit the range of the partial image by detecting a window frame byimage processing such as template matching. The profile detection means22 may limit the range of the partial image to an existing range of avehicle or an existing range of a window frame, which are detected byusing a laser range scanner, a passage sensor, or the like.

The profile detection means 22 can use an image feature amount based onposition, orientation, strength, and luminance gradient of an edge,which can be calculated from a partial image including a profile outlinefrom forehead to chin, as the image feature amount. The partial imagemay include ears and neck. In some cases, the feature is not wellextracted on this occasion because an outside scene is reflected on awindow glass of the vehicle, the input image is blurred due to movementof the vehicle, or the illuminance inside the vehicle is insufficient.Therefore, the profile detection means 22 may extract the image featureamount after performing preprocessing that alleviates these factors. Forexample, the profile detection means 22 can remove a reflectioncomponent to the window glass by using a polarizing filter by usingpolarization property of specular reflection component. Further, inorder to remove the blur due to movement, the profile detection means 22may estimate the degree of movement blur and perform processing thatrestores an image degraded due to the movement blur. Alternatively, whenthe illuminance is not sufficient, the profile detection means 22 maycorrect contrast by performing processing that uniformizes theilluminance. By doing so, it is possible to improve detection accuracy.

Further, the profile detection means 22 may perform preprocessing (forexample, blurring in the vertical direction) after which vertical edgesremain because a profile outline from forehead to chin and the like aremainly formed by edges in the vertical direction. Thereby, the profiledetection means 22 can reduce influence of a superimposed component ofreflection in directions other than the vertical direction, noise, andthe like, so that the profile detection means 22 can improve a detectionrate. In this case, the profile detection means 22 may estimate thestrength of the superimposed component from a position from which animage of a person is not captured in the window glass of the vehicle,and control the degree of blurring in the vertical direction.

The passenger number determination means 23 determines the number ofpersons present in the vehicle by using the detection result of theprofile detection means 22. Specifically, when the profile detectionmeans 22 outputs whether or not each partial image includes a profile ofa person, the passenger number determination means 23 determines thenumber of partial images determined to include a profile of a person asthe number of persons present in the vehicle. When the profile detectionmeans 22 outputs a score indicating a likeness of a profile of a personin an image included in each partial image, the passenger numberdetermination means 23 determines the number of partial imagesdetermined to include an image that looks like a profile of a person bya comparison between the score and a predetermined score threshold valueas the number of persons present in the vehicle.

When a plurality of partial images can be superimposed, the passengernumber determination means 23 may integrate the partial images into onepartial image. In this case, the passenger number determination means 23may integrate all of the plurality of superimposed partial images intoone partial image, or when a numerical ratio of image ratio of thesuperimposed partial images is greater than a predetermined numericalratio, the passenger number determination means 23 may integrate thesuperimposed partial images into one partial image.

Next, an operation of the passenger counting system of the presentexemplary embodiment will be described. FIG. 3 is a flowchartillustrating the operation of the first exemplary embodiment of thepassenger counting system according to the present invention.

The image acquisition means 21 controls the image capturing device 1 andacquires an image in which the inside of a vehicle is captured (stepA1). The profile detection means 22 sequentially selects partial imagessurrounded by a rectangle with a predetermined aspect ratio, which areobtained from an input image acquired by the image acquisition means 21(step A2). Then, the profile detection means 22 detects a profile of aperson from a partial image based on an image feature amount calculatedby using the partial image (step A3).

When it is determined that the selection of all partial images fromwhich a profile of a person should be detected and the profile detectionfrom the input image are completed (YES in step A4), the passengernumber determination means 23 determines the number of persons presentin the vehicle based on a detection result related to profiles ofpersons outputted by the profile detection means 22 (step A5). When itis determined at step A4 that the selection and the profile detectionare not completed, the processing of step A2 and step A3 is repeated.

The passenger counting system of the present exemplary embodimentdetects profiles of persons from an input image obtained by capturing animage of a vehicle by a camera from outside of the vehicle from thelateral direction of the vehicle. Thereby, the passenger counting systemcan detect a person sitting on the back seat of the vehicle, who ispossibly not able to capture sufficiently in an image obtained byphotographing the vehicle from the front of the vehicle. Therefore, thepassenger counting system of the present exemplary embodiment can countcorrectly the number of persons present in a vehicle, including personssitting on the back seat.

Second Exemplary Embodiment

FIG. 4 is an explanatory diagram illustrating an overview of the secondexemplary embodiment of the passenger counting system according to thepresent invention. FIG. 5 is a block diagram illustrating aconfiguration of the second embodiment of the passenger counting systemaccording to the present invention. In the description below, thedescription of the same parts as those of the first exemplary embodimentwill be omitted.

As illustrated in FIGS. 4 and 5, the passenger counting system of thepresent exemplary embodiment is different from the passenger countingsystem of the first exemplary embodiment illustrated in FIG. 2 in apoint that an image capturing device 3 that captures an image inside avehicle from the front of the vehicle is further included. Asillustrated in FIG. 5, a passenger counting device 4 of the passengercounting system of the present exemplary embodiment is different fromthe passenger counting system of the first exemplary embodiment in apoint that the passenger counting device 4 further includes an imageacquisition means 24 and a frontal face detection means 25 and includesa passenger number determination means 26 instead of the passengernumber determination means 23.

The image capturing device 3 may be a still camera that captures a stillimage or a video camera that captures a moving image.

The image acquisition means 24 controls the image capturing device 3 andacquires an image in which the inside of the vehicle is captured. Atthis time, the image acquisition means 24 may acquire an image in whicha vehicle of an image capturing target is captured by controlling theimage capturing device 3 according to passing timing of the vehicle,which is obtained from a sensor that detects the presence of thevehicle, such as a passage sensor and a weight sensor arranged on acourse on which the vehicle travels. The image acquisition means 24 maydetermine whether or not an image of the inside of the vehicle iscaptured in each image obtained by controlling the image capturingdevice 3 to continuously capture a plurality of images by imageprocessing such as detecting a window frame by template matching, andmay acquire an image in which the inside of the vehicle, which is animage capturing target, is captured.

For example, when the image acquisition means 24 controls the imagecapturing device 3 by using a passage sensor, the image capturing device3 and the passage sensor are installed after the positional relationshipbetween the image capturing device 3 and the passage sensor aredetermined so that the image capturing device 3 can capture a person ona front seat when the passage sensor detects a vehicle. The imageacquisition means 24 can capture the person on the front seat at adesired angle of view by capturing an image of the inside of the vehicleby controlling the image capturing device 3 according to detectiontiming of the passage sensor. Further, the image acquisition means 24may acquire a plurality of images in which a vehicle is captured whichis an image capturing target.

The frontal face detection means 25 calculates the image feature amountby using a partial image surrounded by a rectangle with a predeterminedaspect ratio, which is obtained from an image (hereinafter referred toas an input image) acquired by the image acquisition means 24. Then, thefrontal face detection means 25 detects a frontal face of a person fromthe input image by determining whether or not the partial image includesa frontal face of a person based on the image feature amount. Thefrontal face detection means 25 may output information indicatingwhether or not each partial image is a frontal face of a person as adetection result or may output a score indicating a likeness of afrontal face of a person in an image included in each partial image as adetection result.

The frontal face detection means 25 may determine a range of the partialimage based on the size of a frontal face of a person in an input image,which varies according to the distance between the image capturingdevice 3 and the vehicle. The frontal face detection means 25 may limitthe range of the partial image to a predetermined range in which insideof a vehicle may be captured. The frontal face detection means 25 maylimit the range of the partial image to a range in which the inside of avehicle is captured, which is determined by image processing such asdetecting a window frame by template matching. The frontal facedetection means 25 may limit the range of the partial image to anexisting range of a vehicle or an existing range of a window frame,which are detected by using a laser range scanner, a passage sensor, orthe like.

The passenger number determination means 26 determines the number ofpersons present in the vehicle based on a person profile detectionresult obtained by the profile detection means 22 and a person frontalface detection result obtained by the frontal face detection means 25.Specifically, the passenger number determination means 26 determines themaximum value, the average value, or the sum of the number of profilesobtained by the profile detection means 22 and the number of frontalfaces obtained by the frontal face detection means 25 as the number ofpersons present in the vehicle.

When the detection result of the profile detection means 22 is theinformation indicating whether or not each partial image includes aprofile of a person, the number of profiles is the number of partialimages determined to be a profile of a person. When the detection resultof the profile detection means 22 is the score indicating a likeness ofa profile of a person of each partial image, the number of profiles isthe number of partial images determined to be like a profile of a personby a comparison between the score and a predetermined score thresholdvalue. When the detection result of the frontal face detection means 25is information indicating whether or not each partial image includes afrontal face of a person, the number of frontal faces is the number ofpartial images determined to include a frontal face of a person. Whenthe detection result of the frontal face detection means 25 is the scoreindicating a likeness of a frontal face of a person of an image includedin each partial image, the number of frontal faces is the number ofpartial images including an image determined to be like a frontal faceof a person by a comparison between the score and a predetermined scorethreshold value.

At this time, when a plurality of partial images can be superimposed,the passenger number determination means 26 may integrate the partialimages into one partial image. In this case, the passenger numberdetermination means 26 may integrate all of the plurality ofsuperimposed partial images into one partial image, or when a numeralratio of the superimposed partial images is greater than a predeterminednumeral ratio, the passenger number determination means 26 may integratethe superimposed partial images into one partial image.

As another specific example, the passenger number determination means 26associates a position of each partial image that is determined toinclude a face of a person by the profile detection means 22 and thefrontal face detection means 25 with a position of a seat inside thevehicle that is an image capturing target. Then, the passenger numberdetermination means 26 determines whether or not the seat positioninside the vehicle of each partial image that is determined to include aprofile of a person by the profile detection means 22 overlaps the seatposition inside the vehicle of each partial image that is determined toinclude a frontal face of a person by the frontal face detection means25. Thereby, the passenger number determination means 26 determines atotal number of seat positions where persons sit and may determine thenumber of persons present in the vehicle based on the total number. Forexample, when the number of profiles is four, the number of frontalfaces is four, and the number of overlapped seat positions is three, thenumber of seat positions that do not overlap each other is one in eachnumber, so that the passenger number determination means 26 determinesthat the total number of persons is five.

Next, an operation of the passenger counting system of the presentexemplary embodiment will be described. FIG. 6 is a flowchartillustrating the operation of the second exemplary embodiment of thepassenger counting system according to the present invention.

The image acquisition means 21 and the image acquisition means 24control the image capturing device 1 and the image capturing device 3,respectively, and acquire an image in which the inside of a vehicle iscaptured (step A6). The profile detection means 22 sequentially selectspartial images surrounded by a rectangle with a predetermined aspectratio from an image (hereinafter referred to as a lateral directioninput image) acquired by the image acquisition means 21 (step A2).Further, the profile detection means 22 detects a profile of a personfrom a partial image based on an image feature amount calculated fromthe partial image (step A3).

The frontal face detection means 25 sequentially selects partial imagessurrounded by a rectangle with a predetermined aspect ratio from animage (hereinafter referred to as a front input image) acquired by theimage acquisition means 24 (step A7). The frontal face detection means25 detects a frontal face of a person from a partial image based on animage feature amount calculated from the partial image (step A8). Whenit is determined that the selection of all partial images from which aprofile of a person should be detected and the profile detection fromthe lateral direction input image are completed (YES in step A4) and itis determined that the selection of all partial images from which afrontal face of a person should be detected and the frontal facedetection from the front input image are completed (YES in step A9), thepassenger number determination means 26 determines the number of personspresent in the vehicle based on a detection result related to profilesof persons and a detection result related to frontal faces of persons(step A10).

The passenger counting system of the present exemplary embodimentdetects persons based on an input images obtained by capturing images ofa vehicle by a camera from outside of the vehicle from the lateraldirection and the front direction of the vehicle. Thereby, the passengercounting system of the present exemplary embodiment has an effect thatit is possible to more correctly count the number of persons present inthe vehicle by reducing blind areas due to components of the vehicle andpersons in the vehicle in addition to the effect of the passengercounting system of the first exemplary embodiment.

FIG. 7 is a block diagram illustrating a main part of the passengercounting system according to the present invention. The passengercounting system includes an image capturing device 11 which is arrangedoutside a vehicle and which captures an image of the vehicle from thelateral direction of the vehicle, an image acquisition unit 31 thatcontrols the image capturing device 11 and acquires an image in whichthe inside of the vehicle is captured as an input image, a profiledetection unit 32 that detects a profile of a person from a partialimage obtained from the input image based on an image feature amountcalculated by using the partial image and outputs a detection result,and a passenger number determination unit 33 that determines the numberof persons present in the vehicle based on the detection result.

(1) A passenger counting system including an image capturing device (forexample, the image capturing device 1) which is arranged outside avehicle and which captures an image of the vehicle from the lateraldirection of the vehicle, an image acquisition means (for example, theimage acquisition means 21) that controls the image capturing device andacquires an image in which the inside of the vehicle is captured as aninput image, a profile detection means (for example, the profiledetection means 22) that detects a profile of a person from a partialimage obtained from the input image based on an image feature amountcalculated by using the partial image and outputs a detection result,and a passenger number determination means (for example, the passengernumber determination means 23) that determines the number of personspresent in the vehicle based on the detection result.(2) The passenger counting system may be configured so that the imageacquisition means acquires an image in which the inside of the vehicleis captured as an input image by controlling the image capturing deviceaccording to passing timing of the vehicle, which is obtained by asensor that is arranged on a course on which the vehicle travels anddetects the presence of the vehicle.(3) The passenger counting system may be configured so that the imageacquisition means determines whether or not the inside of the vehicle iscaptured in a plurality of images that is continuously captured bydetecting a window frame by using image processing using templatematching and acquires an image in which the inside of the vehicle iscaptured as an input image.(4) The passenger counting system may be configured so that the profiledetection means uses an image feature amount based on position,orientation, strength, and luminance gradient of an edge, which can becalculated from a partial image including a profile outline fromforehead to chin, as the image feature amount.(5) The passenger counting system may be configured so that the profiledetection means applies preprocessing to the input image so thatvertical edges remain in the input image.(6) The passenger counting system may be configured so that the profiledetection means limits a range in the input image, from which a partialimage is cut out, to a predetermined range in which inside of a vehiclemay be captured, a range in which the inside of a vehicle, which isdetermined by detecting a window frame by using image processing usingtemplate matching, is captured, or an existing range of a vehicle or anexisting range of a window frame, which are detected by using a laserrange scanner or a passage sensor.(7) The passenger counting system may be configured so that thepassenger number determination means determines the number of partialimages that are determined to include a profile of a person by theprofile detection means as the number of persons present in the vehicle.(8) A passenger counting system including an image capturing device (forexample, the image capturing device 1 and the image capturing device 3)which is arranged outside a vehicle and which captures an image of thevehicle from the lateral direction and the front direction of thevehicle, an image acquisition means (for example, the image acquisitionmeans 21 and the image acquisition means 24) that controls the imagecapturing device, acquires an image in which the inside of the vehicleis captured from the lateral direction as a lateral direction inputimage, and acquires an image in which the inside of the vehicle iscaptured from the front direction as a front input image, a facedetection means (for example, the profile detection means 22 and thefrontal face detection means 25) that detects a profile of a person froma partial image in the lateral direction input image and detects afrontal face of a person from a partial image in the front input imagebased on image feature amounts calculated by using the partial imagesobtained from the lateral direction input image and the front inputimage and outputs a detection result, and a passenger numberdetermination means (for example, the passenger number determinationmeans 26) that determines the number of persons present in the vehiclebased on the detection result.(Supplementary note 1) A passenger counting system may be configured sothat when a plurality of partial images that is determined to include aprofile of a person by a profile detection means can be superimposed, apassenger number determination means performs processing to integratethe plurality of partial images into one partial image and determinesthe number of partial images determined to include a profile of a personafter the processing as the number of persons present in the vehicle.

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2012-231729, filed on Oct. 19,2012, the entire contents of which are incorporated herein by reference.

While the claimed invention has been described with reference to theexemplary embodiments, the claimed invention is not limited to theexemplary embodiments described above. Various modifications apparent tothose skilled in the art may be made on the configuration and details ofthe claimed invention within the scope of the claimed invention.

INDUSTRIAL APPLICABILITY

The present invention is applied to usages such as a system thatdetermines a toll of a toll road according to the number of personspresent in the vehicle and a system that determines whether or not toallow a vehicle to travel in a traffic lane according to the number ofpersons present in the vehicle.

REFERENCE SIGNS LIST

1, 3 Image capturing device

2, 4 Passenger counting device

21, 24 Image acquisition means

22 Profile detection means

23, 26 Passenger number determination means

25 Frontal face detection means

1. A passenger counting system comprising: a first image capturing device having a lens, the first image capturing device being arranged outside a vehicle for capturing a lateral image of inside of the vehicle from a lateral direction of the vehicle; a second image capturing device having a lens, the second image capturing device being arranged outside the vehicle for capturing a frontal image of inside of the vehicle from a frontal direction of the vehicle; and one or more processors configured to: detect a number of faces from the lateral image; detect a number of faces from the frontal image; and determine a number of persons present in the vehicle based on the number of faces detected from the lateral image and the number of faces detected from the frontal image.
 2. The passenger counting system according to claim 1, the processor further configured to: detect a number of profiles in order to detect the number of faces from the lateral image; detect a number of frontal faces in order to detect the number of faces from the frontal image, wherein the processor determines a number of persons present in the vehicle based on the number of profiles and the number of frontal faces.
 3. The passenger counting system according to claim 1, the processor further configured to: when a position of a face detected from the lateral image and a position of a face detected from the frontal image overlap, count the overlapping faces as one person present in the vehicle.
 4. A passenger counting method comprising: capturing a lateral image of inside of a vehicle from a lateral direction of the vehicle by a first image capturing device arranged outside the vehicle; capturing a frontal image of inside of the vehicle from a frontal direction of the vehicle by a second image capturing device arranged outside the vehicle; detecting a number of faces from the lateral image; detecting a number of faces from the frontal image; and determining a number of persons present in the vehicle based on the number of faces detected from the lateral image and the number of faces detected from the frontal image.
 5. A non-transitory computer readable information recording medium storing a passenger counting program that, when executed by a processor, performs a method for: acquiring a lateral image of inside of a vehicle captured from a lateral direction of the vehicle; acquiring a frontal image of inside of the vehicle captured from a frontal direction of the vehicle; detecting a number of faces from the lateral image; detecting a number of faces from the frontal image; and determining a number of persons present in the vehicle based on the number of faces detected from the lateral image and the number of faces detected from the frontal image. 